The European Union, which launched its digital COVID certificate last week, has so far authorised only four vaccines - those of Pfizer Inc (PFE.N) and BioNTech (22UAy.DE), Moderna Inc (MRNA.O), AstraZeneca (AZN.L) and Johnson & Johnson (JNJ.N).
The certificate allows citizens to travel more freely across the bloc if they have been fully vaccinated with one of the four approved shots, received a recent negative test result or have immunity due to recent recovery.
Member states can decide to extend the certificate to European travellers vaccinated with other shots.
Mainland Portugal only accepts the four vaccines, but Madeira, an autonomous region popular for its wine and green landscape, said those who received other shots, such as those of China's Sinovac (SVA.O) or India's Covaxin, could visit the Atlantic islands.
Pedro Ramos, Madeira's health secretary, said all would be accepted "because if millions have been vaccinated with these vaccines (not approved by the EU), their level of protection is similar to others".
It comes amid criticism over the EU not including Covishield, a version of AstraZeneca's COVID-19 vaccine made by Serum Institute in India, on a list of approved vaccines for the certificate.
About 5 million people in Britain, an important source of foreign tourism for Madeira, are thought to have had the Covishield vaccine, which is also used by the global COVAX facility. Reporting by Catarina Demony; Editing by Peter Cooney